TW202017032A - Polish head of chemical mechanical polishing apparatus and chemical mechanical polishing method - Google Patents

Abstract

A polish head of a chemical mechanical polishing system is provided. The polish head includes a carrier head, a membrane mounted to the carrier head, an inner retaining ring mounted to the carrier head and surrounding the membrane, an outer retaining ring mounted to the carrier head and surrounding the inner retaining ring, and an image capturing device. The outer retaining ring is spaced apart from the inner retaining ring. The image capturing device is mounted to the carrier head and between the inner retaining ring and the outer retaining ring.

Description

Chemical mechanical polishing device and method

In general, semiconductor elements include active components formed on a substrate, such as transistors. Any number of interconnect layers can be formed on the substrate to connect the active components to each other and to external components. The interconnect layer may be made of a low dielectric constant dielectric material, including metal-containing trenches/vias.

When forming an element layer, it is sometimes necessary to planarize the element. For example, the formation of metal features in the substrate or in the metal layer may cause uneven topography. This uneven topography creates difficulties in the formation of subsequent layers. For example, uneven topography may interfere with the photolithography process used to form various features in the device. Therefore, it is necessary to flatten the surface of the element after forming various features or layers. One method of planarization is chemical mechanical polishing (CMP).

10‧‧‧ Wafer

20‧‧‧Slurry

100‧‧‧Chemical mechanical grinding system

110‧‧‧platform

120‧‧‧Abrasive pad

140‧‧‧ Regulator

142‧‧‧Adjustment arm

144‧‧‧Adjustment pad

150‧‧‧Slurry dispenser

152‧‧‧ Dispenser arm

154‧‧‧ nozzle

200‧‧‧Grinding head

210‧‧‧Carrier head

220‧‧‧Inner ring

222‧‧‧Outside wall

230‧‧‧Outer fixing ring

232‧‧‧ Wall part

234‧‧‧Flange

236‧‧‧Inner side wall

238‧‧‧Top surface

240‧‧‧membrane

250‧‧‧Image capture component

252‧‧‧Light source

254‧‧‧ optical receiver

255‧‧‧ processor

260‧‧‧groove

262‧‧‧groove

265‧‧‧ Orbit

270‧‧‧Bracket

272‧‧‧bearing roller

274‧‧‧Guide roller

S12‧‧‧Step

S14‧‧‧Step

S16‧‧‧Step

G‧‧‧Gap

d‧‧‧Distance

W‧‧‧Width

When reading in conjunction with the accompanying drawings, the state of the disclosure is best understood from the following detailed description. It should be noted that according to standard industry practice, various features are not drawn to scale. In fact, for clarity of discussion, various features may be arbitrarily increased or decreased in size.

Figure 1 is a schematic diagram of a chemical mechanical polishing system according to some embodiments of the present disclosure.

Figure 2 is a top view of the chemical mechanical polishing system of Figure 1.

Figure 3 is a cross-sectional view of the polishing head of Figure 1.

Figure 4 is a bottom view of the polishing head of Figure 1.

Figure 5 is a cross-sectional view taken along line 5 of Figure 4.

Figure 6 is a bottom view of an abrasive head according to some other embodiments of the present disclosure.

Figure 7 is a flowchart of a method for operating the chemical mechanical polishing system of Figure 1.

The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are only examples and are not intended to be limiting. For example, the formation of the first feature on or above the second feature in the following description may include embodiments in which the first feature and the second feature are formed in direct contact, and may also include additional features An embodiment may be formed between the first feature and the second feature so that the first feature and the second feature may not directly contact. In addition, the present disclosure may repeat element symbols and/or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not in itself represent the relationship between the various embodiments and/or configurations discussed.

Further, for simplicity of the description, can be used herein such as "below the _......", "below ......", "lower portion", "above ......", "upper" and the like spatial terms of relative terms To describe the relationship between one element or feature and another (other) element or feature as illustrated in the figures. In addition to the orientations depicted in the figures, such spatial relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly accordingly.

FIG. 1 is a schematic diagram of a chemical mechanical polishing system 100 according to some embodiments of the present disclosure. FIG. 2 is a top view of the chemical mechanical polishing system 100 of FIG. 1. The chemical mechanical polishing system 100 is used to perform a planarization process on the wafer 10 in the semiconductor manufacturing process. According to some embodiments of the present disclosure, the chemical mechanical polishing system 100 includes a platform 110, a polishing pad 120, a polishing head 200, a regulator 140, and a slurry dispenser 150. The table 110 is driven by a motor to rotate the polishing pad 120 around the rotation axis. In some embodiments, the platform 110 is circular in a top view. The diameter of the platform 110 is larger than the diameter of the wafer 10 to be polished.

The abrasive pad 120 is placed on the platform 110. The abrasive pad 120 may be a consumable item. The abrasive pad 120 may be a relatively hard and incompressible pad or a soft pad. For oxidative grinding, a harder pad can be used to achieve a flat surface. Softer pads can be used in other grinding processes to achieve a uniform and smooth surface. In custom applications, the arrangement of stacked pads can also be used to combine hard and soft pads.

The polishing head 200 is used to accommodate the wafer 10. In some embodiments, the grinding head 200 includes a carrier head 210, a membrane 240, and at least one fixing ring. In some embodiments, the fixing ring includes an outer fixing ring 230 and an inner fixing ring 220. The inner fixing ring 220 is placed between the outer fixing ring 230 and the membrane 240. The outer fixing ring 230 and the inner fixing ring 220 can adjust the surface profile of the polishing pad 120 and control the wafer edge profile.

The carrier head 210 picks up the wafer 10 from the platform using vacuum suction on the film 240, for example. The carrier head 210 carries the wafer 10 to the polishing pad 120, and the carrier head 210 is lowered toward the polishing pad 120 to polish the wafer 10. The film 240 under the carrier head 210 is pressed to push the wafer 10 toward the polishing pad 120. The wafer 10 is polished by rotating the polishing pad 120 (and/or the carrier head 210). The wafer 10 may have various device elements thereon. Examples of device elements formed on the wafer 10 include transistors (eg, metal oxide semiconductor field effect transistors (MOSFETs), complementary metal oxide semiconductor (CMOS) circuits Crystals, bipolar junction transistors (BJT), high-voltage transistors, high-frequency transistors, p-channel and/or n-channel field effect transistors (p-channel field-effect transistor/n-channel field -effect transistor; PFET/NFET), etc.), diodes and/or other suitable components. Various processes can be performed to form device elements, such as deposition, etching, implantation, photolithography, annealing, and/or other suitable processes. In some embodiments, a shallow trench isolation may also be formed in or on the wafer 10 Isolation (STI) structure, inter-layer dielectric (ILD) layer and/or inter-metal dielectric layer.

The adjuster 140 is used to adjust the abrasive pad 120. In some embodiments, the adjuster 140 includes an adjustment arm 142 and an adjustment pad 144. The adjustment arm 142 holds the adjustment pad 144 which is in contact with the abrasive pad 120 during the planarization process. The adjustment arm 142 moves the adjustment pad 144 over the area of the abrasive pad 120 in a sweeping motion. The adjustment pad 144 includes a substrate over which an array of abrasive particles (such as diamond) is bonded using, for example, electroplating. The adjustment pad 144 removes accumulated wafer debris and excess slurry from the abrasive pad 120. The adjustment pad 144 also serves as an abrasive for the abrasive pad 120 to form a suitable texture against which the wafer 10 can be properly planarized.

The slurry dispenser 150 includes a dispenser arm 152 and a plurality of nozzles 154. The nozzle 154 is arranged on the bottom surface of the applicator arm 152 and serves to supply the slurry 20 above the abrasive pad 120. The composition of the slurry 20 supplied by the slurry dispenser 150 depends on the type of material on the surface of the wafer subjected to CMP. For example, the tungsten paste may be acidic to enhance the chemical etching effect on the tungsten film; and the copper paste may be alkaline to minimize corrosion of the copper film.

In some embodiments, one or more elements may be added to or omitted from the chemical mechanical grinding system 100. For example, a sprayer nozzle may be added to the chemical mechanical polishing system 100, and this sprayer nozzle is used to supply high-pressure rinse on the polishing pad 120, thereby cleaning the polishing pad 120.

Refer to Figure 3 and Figure 4. FIG. 3 is a cross-sectional view of the polishing head 200 of FIG. 1. FIG. 4 is a bottom view of the polishing head 200 of FIG. research The grinding head 200 includes a bearing head 210, an inner fixing ring 220, an outer fixing ring 230, a membrane 240, and an image capturing element 250. The carrier head 210 is used to accommodate the wafer therein. The inner fixing ring 220 and the outer fixing ring 230 are used to fix the wafer in a horizontal position. The film 240 is used to fasten the wafer and press the wafer in a downward direction.

The inner fixing ring 220 and the outer fixing ring 230 are coaxially arranged. The membrane 240 is mounted to the carrier head 210. The inner fixing ring 220 is mounted to the carrier head 210 and surrounds the membrane 240. The outer fixing ring 230 is mounted to the carrier head 210 and surrounds the inner fixing ring 220. The outer fixing ring 230 is separated from the inner fixing ring 220. The outer fixing ring 230 is formed with a wall portion 232 and a flange portion 234. The flange portion 234 extends horizontally from the wall portion 232 toward the inner fixing ring 220, and the bottom surface of the flange portion 234 is substantially coplanar with the bottom surface of the wall portion 232. During the chemical mechanical polishing process, the flange portion 234 of the outer fixing ring 230 may be in contact with the inner fixing ring 220 and used to fix the inner fixing ring 220 at a horizontal position by restricting the horizontal movement of the inner fixing ring 220. The inner fixing ring 220 is then used to fix the wafer at a horizontal position by restricting the horizontal movement of the wafer. The inner side wall 236 of the wall portion 232 of the outer fixing ring 230 facing the inner fixing ring 220 and the outer side wall 222 of the inner fixing ring 220 facing the outer fixing ring 230 define a gap G between the inner side wall 236 and the outer side wall 222.

In some embodiments, the inner retaining ring 220 comprises polyurethane, polyester, polyether, polycarbonate, any combination thereof, or any other suitable material. In some embodiments, the outer retaining ring 230 comprises polyetheretherketone (PEEK), polyphenylene sulfide (PPS), any combination thereof, or any other suitable material. In some embodiments, the inner retaining ring 220 is softer than the outer retaining ring 230 in hardness. in In some embodiments, the inner retaining ring 220 has a hardness on the Shore A hardness scale of about 15 to about 105, and the outer retaining ring 230 has a Rockwell M hardness on the Rockwell M hardness scale. scale) in the range of about 95 to about 110 hardness. The softer inner retaining ring 220 absorbs impact/contact energy during the chemical mechanical polishing process and reduces vibration between the inner retaining ring and the wafer, and prevents damage/flaking on the wafer.

Shore hardness is a measure of the penetration resistance of a calibrated spring-loaded needle indenter by using a material measured by hardness. The Shore hardness scale is used to measure the hardness of polymers (rubber, plastic). Rockwell hardness is measured by pressing a test material with a diamond cone or hardened steel ball indenter. The indenter is forced into the test material under an initial light load, and the application and removal of the additional main load result in a permanent increase in the penetration depth used to calculate the Rockwell hardness value.

In some embodiments, the inner diameter of the inner fixing ring 220 ranges from about 300 mm to about 303 mm, and the outer diameter of the outer fixing ring 230 ranges from about 329 mm to about 333 mm. In some other embodiments, the size of the inner retaining ring 220 and the outer retaining ring 230 may be different to accommodate larger or smaller wafers during the chemical mechanical polishing process or other processes that require wafers to be fixed in the process steps.

In some embodiments, the inner retaining ring 220 has a thickness ranging from about 31 mm to about 35 mm. In some embodiments, the outer retaining ring 230 has a thickness ranging from about 25 mm to about 28 mm. In some embodiments, the thickness of the inner retaining ring 220 is thicker than the thickness of the outer retaining ring 230, and the thickness difference is in the range from about 6 mm to about 8 mm. If the thickness difference between the inner fixing ring 220 and the outer fixing ring 230 is greater than about 8 mm, the inner fixing ring 220 It may be too thick so that the contact area between the inner retaining ring 220 and the abrasive pad is too large, and therefore undesirable particles may be formed due to friction between the inner retaining ring 220 and the abrasive pad. If the thickness difference between the inner fixing ring 220 and the outer fixing ring is less than about 6 mm, the inner fixing ring 220 may be too thin to have satisfactory mechanical strength.

In some embodiments, both the inner fixing ring 220 and the outer fixing ring 230 are attached to the bottom surface of the carrier head 210 using an adhesive (adhesive) layer.

However, during the chemical mechanical polishing process, due to friction between the flange portion 234 of the outer fixing ring 230 and the inner fixing ring 220, the flange portion 234 of the outer fixing ring 230 may be worn, and the wall portion of the outer fixing ring 230 232 may improperly contact inner retaining ring 220. In this case, the contact between the wall portion 232 of the outer fixing ring 230 and the inner fixing ring 220 causes undue friction between the wall portion 232 of the outer fixing ring 230 and the inner fixing ring 220. Improper friction between the wall portion 232 of the outer fixing ring 230 and the inner fixing ring 220 may cause defects on the wafer. In some embodiments, the gap G between the inner side wall 236 of the wall portion 232 of the outer fixing ring 230 and the outer side wall 222 of the inner fixing ring 220 is in the range from about 1.37 mm to about 2.06 mm to prevent the outer fixing ring The wall portion 232 of 230 improperly contacts the inner fixing ring 220.

In some embodiments, the image capturing element 250 of the grinding head 200 is mounted to the carrier head 210 and is arranged in the gap G between the outer fixing ring 230 and the inner fixing ring 220 and used to capture the outer fixing ring 230 Images of the top surface 238 of the flange portion 234, the inner side wall 236 of the wall portion 232 of the outer retaining ring 230, and the outer side wall 222 of the inner retaining ring 220. For example, in In some embodiments, at least a portion of the image capture element 250 is directly above the flange portion 234.

In some embodiments, the captured images are analyzed to determine whether the width W of the flange portion 234 of the outer fixing ring 230 is less than a predetermined value. When it is determined that the width W of the flange portion 234 of the outer fixing ring 230 is smaller than a predetermined value, a warning is issued. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the outer retaining ring 230.

In some embodiments, the width W of the flange portion 234 of the outer fixing ring 230 is in the range from about 0.77 mm to about 1.26 mm to prevent the wall portion 232 of the outer fixing ring 230 from improperly contacting the inner fixing ring 220. If the width W of the flange portion 234 of the outer fixing ring 230 is less than about 0.77 mm, it is determined that the outer fixing ring 230 has worn out, and a warning is issued. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the outer retaining ring 230.

In some embodiments, the captured images are analyzed to determine whether the distance d between the side wall of the flange portion 234 of the outer fixing ring 230 and the outer side wall 222 of the inner fixing ring 220 is greater than a predetermined value. When it is determined that the distance d between the side wall of the flange portion 234 of the outer fixing ring 230 and the outer side wall 222 of the inner fixing ring 220 is greater than a predetermined value, a warning is issued. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the inner fixing ring 220 and/or the outer fixing ring 230.

In some embodiments, the distance d between the side wall of the flange portion 234 of the outer fixing ring 230 and the outer side wall 222 of the inner fixing ring 220 is in the range from about 0.6 mm to about 0.8 mm to prevent the outer fixing ring 230 The wall portion 232 improperly contacts the inner fixing ring 220. If the side wall of the flange portion 234 is determined If the distance d between the inner fixing ring 220 and the outer side wall 222 is greater than 0.9 mm, and/or the ratio of the width W to the distance d is less than about 0.3, it is determined that the inner fixing ring 220 and/or the outer fixing ring 230 have worn out, and warning. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the inner fixing ring 220 and/or the outer fixing ring 230.

Other features that can be observed from the captured images include the roughness of the inner side wall 236 of the wall portion 232 of the outer fixing ring 230, the roughness of the outer side wall 222 of the inner fixing ring 220, and the inside of the wall portion 232 of the outer fixing ring 230 The inclination angle of the side wall 236 and the inclination angle of the outer side wall 222 of the inner fixing ring 220. If the roughness of the inner sidewall 236 of the wall portion 232 of the outer fixing ring 230, the roughness of the outer sidewall 222 of the inner fixing ring 220, the inclination angle of the inner sidewall 236 of the wall portion 232 of the outer fixing ring 230, and/or the inner fixing ring If the inclination angle of the outer side wall 222 of 220 is determined to be unacceptable, it is determined that the inner fixing ring 220 and/or the outer fixing ring 230 have worn out and a warning is issued. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the inner fixing ring 220 and/or the outer fixing ring 230.

In addition, the inner fixing ring 220 has a groove 260 in the bottom surface of the inner fixing ring 220, and the outer fixing ring 230 has a groove 262 in the bottom surface of the outer fixing ring 230. The grooves 262 of the outer retaining ring 230 are respectively substantially aligned with the grooves 260 of the inner retaining ring 220 to form continuous channels that allow the slurry to flow to the wafer during the chemical mechanical polishing process. In some embodiments, the groove 262 of the outer fixing ring 230 may have a width greater than the width of the groove 260 of the inner fixing ring 220. However, when the slurry flows through the channel, the slurry passes through the gap G between the outer fixing ring 230 and the inner fixing ring 220, and may Improperly penetrates into the gap G, thereby leaving contaminant residue inside the gap G between the outer fixing ring 230 and the inner fixing ring 220. Contaminant residues inside the gap G between the outer fixing ring 230 and the inner fixing ring 220 can also cause defects on the wafer.

In some embodiments, the captured images are analyzed to determine whether the contaminant residue inside the gap G exceeds a predetermined threshold. When it is determined that the contaminant residue inside the gap G exceeds a predetermined threshold, a warning is issued. In some embodiments, when a warning is issued, a cleaning process is performed on the grinding head 200 to remove contaminant residue from the gap G.

In some embodiments, because part of the contaminant residue inside the gap G is deposited on the top surface 238 of the flange portion 234 of the outer retaining ring 230, the captured images are analyzed to determine the flange portion of the outer retaining ring 230 Whether the contaminant residue on the top surface 238 of 234 exceeds a predetermined threshold. When it is determined that the contaminant residue on the top surface 238 of the flange portion 234 of the outer fixing ring 230 exceeds a predetermined threshold, a warning is issued. In some embodiments, when a warning is issued, a cleaning process is performed on the grinding head 200 to remove contaminant residue from the gap G.

In some embodiments, the gap G is in fluid communication with the groove 260 of the inner retaining ring 220 and the groove 262 of the outer retaining ring 230 at the junction. The image capturing element 250 is configured so that the image capturing element 250 can capture an image of a portion of the gap G adjacent to the junction. For example, in some embodiments, the image capture element 250 is coupled to the rail 265, which allows the image capture element 250 to move to a position immediately adjacent to the junction. In some other embodiments In this case, the image capturing element 250 is placed immediately adjacent to the junction (as shown in Figure 6).

In some embodiments, the image capturing element 250 is an image sensor with a large effective area. For example, the image capturing element 250 may be a photodiode, such as an indium gallium arsenide (InGaAs) photodiode. InGaAs photodiodes can detect images in low light conditions, making them suitable for capturing images inside the gap G. Save the detected image as a grayscale image with 16 bits or more per pixel sample. In other words, each pixel in the stored image can be represented by a light intensity of 216 or 65,536 or higher. The intensity at the corresponding pixel may not be spaced linearly proportional to the detected physical light. The fact is that it can be evenly distributed on the gamma-compressed nonlinear scale to produce a smoother image without significant discontinuous pixels. The resulting stored image shows sharp contrast of detail.

In some embodiments, the image capture device 250 may use high dynamic range. High dynamic range displays image features with clear boundaries and a brightness range similar to the brightness range visible to the human eye. In this way, the displayed image is easy for human eyes to interpret and recognize the features detected by the image capturing element 250.

In some embodiments, the image captured by the image capturing element 250 is processed by the processor 255. The processor 255 processes the captured images to calculate the wear level of the outer fixing ring 230, such as the wear level of the flange portion 234 of the outer fixing ring 230. In some embodiments, the image capturing element 250 is used to scan the target area, and the processor 255 is used to calculate the target area The area of the largest object. If the target area is in the gap G between the inner fixing ring 220 and the outer fixing ring 230, the area of the largest object in the target area is the area of the top surface 238 of the flange portion 234 of the outer fixing ring 230. However, if the flange portion 234 of the outer retaining ring 230 has worn away, the area of the top surface 238 of the flange portion 234 is substantially reduced. In this way, the area of the largest object in the target area is reduced. By calculating the area of the largest object in the target area, the processor can recognize the wear level on the flange portion 234 of the outer fixing ring 230. In some embodiments, if the area of the largest object is greater than a predetermined value, the processor does not issue a warning; and if the area of the largest object is less than the predetermined value, a warning is issued. In some embodiments, when a warning is issued, preventive maintenance is performed to replace the outer retaining ring 230 with a new outer retaining ring.

Refer to Figure 4 and Figure 5. Figure 5 is a cross-sectional view taken along line 5 of Figure 4. The grinding head 200 further includes a track 265 in the carrier head 210. The rail 265 is a circular rail, and is disposed in the peripheral area of the grinding head 200 and above the gap G between the inner fixing ring 220 and the outer fixing ring 230. The track 265 generally extends along the gap G. The image capturing element 250 is coupled to the rail 265 and can move along the rail 265 and thus can move along the gap G. In some embodiments, the image capturing element 250 includes a light source 252 and a light receiver 254. The light source 252 and the light receiver 254 are disposed on the bottom surface of the bracket 270 and face the gap G. The bracket 270 is held by the rail 265. In some embodiments, a plurality of bearing rollers 272 are placed between the bottom portion of the track 265 and the bracket 270. The bracket 270 and the image capturing element 250 are supported by the bearing roller 272. The bracket 270 is connected to and driven by the motor so that the bracket 270 and the image capturing element 250 can move along the rail 265. In some embodiments In this case, a plurality of guide rollers 274 are placed between the bracket 270 and the side wall of the rail 265, so that the movement of the bracket 270 can be more stable.

In some other embodiments, as shown in FIG. 6, a plurality of image capturing elements 250 are arranged along the gap G between the inner fixing ring 220 and the outer fixing ring 230 of the grinding head 200. Each of the image capturing elements 250 is immovable, and is used to capture images at its position. In some embodiments, the image capturing elements 250 may be arranged at regular intervals.

Refer to Figure 1, Figure 2, and Figure 7. FIG. 7 is a flowchart of a method for operating the chemical mechanical polishing system 100 of FIG. In step S12, a chemical mechanical polishing process is performed on the wafer 10 using the chemical mechanical polishing system 100. During the chemical mechanical polishing process, the slurry 20 is supplied to the polishing pad 120. For example, the slurry 20 is supplied by the slurry dispenser 150, and at least one of the nozzles 154 drops the slurry 20 on the polishing pad 120. The table 110 is driven by a motor to rotate the polishing pad 120 around the rotation axis. The wafer 10 is fastened upside down in the polishing head 200, surrounded by the inner fixing ring 220, and under the membrane 240. The polishing head 200 descends to the polishing pad 120 and presses the wafer 10 against the polishing pad 120. In some embodiments, after the polishing head 200 descends to the polishing pad 120, the film 240 of the polishing pad 120 is pressed to push the wafer 10 toward the polishing pad 120.

The grinding head 200 is driven by a drive shaft to rotate or oscillate. In some embodiments, the oscillating path of the polishing head 200 is along the radial direction of the polishing pad 120. When the polishing head 200 rotates and sweeps across the polishing pad 120, the outer fixing ring 230 fixes the inner fixing ring 220 at a horizontal position, and the inner fixing ring 220 then fixes the wafer 10 at the horizontal position. Slurry 20 flows through the outer retaining ring 230 The groove 260 (see FIG. 4) and the groove 262 (see FIG. 4) of the inner ring 220 flow to the wafer 10.

The regulator 140 is pressed against the polishing pad 120 and caused to rotate and oscillate so as to maintain a uniform surface on the polishing pad 120.

In step S14, the image capturing element 250 is used to capture the image of the gap between the outer fixing ring 230 and the inner fixing ring 220. In some embodiments, after completing a single chemical mechanical polishing process of the wafer 10, the image capturing element 250 is moved along the gap between the inner fixed ring 220 and the outer fixed ring 230, and then the image of the gap is captured . In some embodiments, the image capturing element 250 captures images of the gap at regular intervals as it moves along the gap between the inner fixed ring 220 and the outer fixed ring 230.

In some other embodiments, as shown in FIG. 6, a plurality of image capturing elements 250 are arranged inside the gap between the inner fixing ring 220 and the outer fixing ring 230 of the grinding head 200. The image capturing element 250 is immovable, and in step S14, the image capturing element 250 captures an image at its position.

Refer to Figure 5. In some embodiments, during each image capturing operation, the light source 252 of the image capturing element 250 is turned on to illuminate the gap G between the inner fixing ring 220 and the outer fixing ring 230, and the image capturing element 250 The light receiver 254 captures light reflected from the inner side wall 236 of the wall portion 232 of the outer fixing ring 230, the outer side wall 222 of the inner fixing ring 220, and/or the top surface 238 of the flange portion 234. In some embodiments, the light source 252 is continuously on during the plurality of capture operations; in some other embodiments, the light source 252 is a pulsed light source and is turned on during each capture operation and after each capture operation shut down.

Refer to Figure 1 and Figure 7. In step S16, the image captured by the image capturing element 250 is analyzed to identify any possible defects. Possible defects may include gaps between the inner retaining ring 220 and the outer retaining ring 230 and/or contaminant residues on the top surface of the flange portion of the outer retaining ring 230, and/or the outer retaining ring 230 and/or Wear on the inner retaining ring 220. If any defect is detected, a warning is issued, and in response to this alarm, a cleaning process and/or preventive maintenance is performed to remove the defect.

In some embodiments, steps S14 and S16 may be taken after grinding each wafer or at the end of the entire chemical mechanical polishing process. In other words, steps S14 and S16 can be taken at the end of each cycle of step S12. In some other embodiments of the present disclosure, steps S14 and S16 may be taken after repeating one of the series of steps 12 multiple times.

Some embodiments of the present disclosure provide a grinding head having an image capturing element disposed between an inner fixing ring and an outer fixing ring. The image capturing element is used to capture the image of the gap between the inner fixing ring and the outer fixing ring. The captured images can be analyzed to identify any possible defects.

According to some embodiments of the present disclosure, a grinding head for a chemical mechanical grinding system is provided. The polishing head includes a bearing head, a film mounted on the bearing head, an inner fixing ring mounted on the bearing head and surrounding the film, a fixing ring mounted on the bearing head and surrounding the inner fixing ring, and an image capturing element. The outer fixing ring is separated from the inner fixing ring. The image capturing element is mounted on the bearing head and between the inner fixing ring and the outer fixing ring.

According to some embodiments of the present disclosure, a method includes performing a chemical mechanical polishing process on a wafer using a chemical mechanical polishing system; and After performing this chemical mechanical polishing process, an image of the gap between the inner and outer fixing rings of the polishing head of the chemical mechanical polishing system is captured.

According to some embodiments of the present disclosure, a method includes picking up a wafer using a polishing head having an inner retaining ring and an outer retaining ring, wherein the outer retaining ring has a wall portion and a flange portion extending from the wall portion toward the inner retaining ring. Grind this wafer. After grinding the wafer, an image of the top surface of the flange portion of the outer retaining ring is captured.

The foregoing outlines the features of several embodiments so that those skilled in the art can better understand the present disclosure. Those skilled in the art should understand that they can easily use this disclosure as a basis for designing or modifying other processes and structures for achieving the same purpose and/or achieving the same advantages of the embodiments described herein. Those skilled in the art should also realize that these equivalent constructions do not deviate from the spirit and scope of this disclosure, and they can make various changes, substitutions, and replacements in this document without departing from the spirit and scope of this disclosure. .

210‧‧‧Carrier head

220‧‧‧Inner ring

222‧‧‧Outside wall

230‧‧‧Outer fixing ring

232‧‧‧ Wall part

234‧‧‧Flange

236‧‧‧Inner side wall

238‧‧‧Top surface

250‧‧‧Image capture component

252‧‧‧Light source

254‧‧‧ optical receiver

265‧‧‧ Orbit

270‧‧‧Bracket

272‧‧‧bearing roller

274‧‧‧Guide roller

G‧‧‧Gap

Claims (20)

A polishing head for a chemical mechanical polishing system, the polishing head includes: A bearing head; A membrane, the membrane is mounted to the carrier; An inner fixing ring, the inner fixing ring is mounted to the bearing head and surrounds the membrane; An outer fixing ring mounted to the carrier head and surrounding the inner fixing ring, wherein the outer fixing ring is spaced from the inner fixing ring; and An image capturing element, the image capturing element is mounted to the bearing head and is between the inner fixing ring and the outer fixing ring. The polishing head according to claim 1, wherein the image capturing element includes a photodiode. The polishing head according to claim 1, wherein the image capturing element includes an indium gallium arsenide photodiode. The polishing head according to claim 1, further includes a track in the carrier head, wherein the image capturing element is coupled to the track. The grinding head as described in claim 4 further includes: A bracket, the image capturing element is on a bottom surface of the bracket; and A plurality of bearing rollers between the track and the bracket. The polishing head according to claim 1, wherein the inner fixing ring has a groove in a bottom surface of the inner fixing ring, and the outer fixing ring has a groove in a bottom surface of the outer fixing ring , And the groove of the inner fixing ring is substantially aligned with the groove of the outer fixing ring. The polishing head according to claim 6, wherein a width of the groove of the outer fixing ring is larger than a width of the groove of the inner fixing ring. The polishing head according to claim 1, wherein the inner fixing ring is softer in hardness than the outer fixing ring. The polishing head according to claim 1, wherein the outer fixing ring has a wall portion and a flange portion extending from the wall portion toward the inner fixing ring. The polishing head according to claim 9, wherein at least a part of the image capturing element is directly above the flange part. One method, including: Using a chemical mechanical polishing (CMP) system to perform a chemical mechanical polishing process on a wafer; and After performing the chemical mechanical polishing process, an image of a gap between an inner fixed ring and an outer fixed ring of a grinding head of the chemical mechanical polishing system is captured. The method of claim 11, wherein capturing the image is performed using an image capturing component; and It further includes: moving the image capturing element along the gap before capturing the image. The method according to claim 11, wherein capturing the image is performed using a plurality of image capturing elements arranged along the gap. The method according to claim 11, wherein the outer fixing ring has a wall portion and a flange portion extending from the wall portion toward the inner fixing ring; It also contains: Analyzing the captured image to determine whether a width of the flange portion of the outer retaining ring is less than a predetermined value; and When it is determined that the width of the flange portion of the outer fixing ring is smaller than the predetermined value, the outer fixing ring is replaced. The method as described in claim 11 further includes: Analyzing the captured image to determine whether a pollutant residue inside the gap exceeds a predetermined threshold; and When it is determined that the pollutant residue inside the gap exceeds the predetermined threshold, the pollutant residue is removed from the gap. The method of claim 11, wherein the inner fixing ring has a groove in a bottom surface of the inner fixing ring, and the outer fixing ring has a groove in a bottom surface of the outer fixing ring, And the gap is in fluid communication with the groove of the inner fixing ring and the groove of the outer fixing ring at a junction; and Wherein the capturing of the image is performed so that a part of the gap adjacent to the junction is in the captured image. One method, including: Using a grinding head with an inner fixing ring and an outer fixing ring to pick up a wafer, wherein the outer fixing ring has a wall portion and a flange portion extending from the wall portion toward the inner fixing ring; and Grinding the wafer; and After grinding the wafer, an image of a top surface of the flange portion of the outer retaining ring is captured. The method as described in claim 17 further includes: Processing the captured image to calculate an area of the top surface of the flange portion of the outer retaining ring; and When the calculated area of the top surface of the flange portion of the outer fixing ring is less than a predetermined value, the outer fixing ring is replaced. The method as described in claim 17 further includes: Processing the captured image to calculate an area of one of the largest objects in the image; and When the calculated area of the largest object in the image is less than a predetermined value, the outer fixing ring is replaced. The method of claim 17, wherein the grinding head has a carrier head and a track in the carrier head; and It further includes: moving the image capturing element along the track before capturing the image.

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